1. Field of the Invention
This invention relates generally to electrical and wave energy chemistry for electroforming alloys from an aqueous bath and more particularly to electroplating a substrate with a permalloy composition to form a thin film on a magnetic recording head.
2. Description of the Prior Art
When a mechanical member is used to agitate an electroplating solution by reciprocating motion, the velocity of that member ranges from 0, at each end of the stroke, to a maximum or peak velocity which is reached between the ends of the stroke. Such changes in the velocity cause uneven boundary layer flow patterns which can result in intolerable non-uniformities in film composition and thickness. This is especially limiting where uniformity is critical as in magnetic recording-head, thin-film electroplating using a permalloy composition. As an example, such thin films can have a thickness of 2 microns and can tolerate a variance of only .+-.0.06 microns.
Both vertical and horizontal plating cells have been used. Of the two, vertical cells are preferred due to easier access to the plated substrates. However, previously known reciprocating agitation, even in vertical cells, is limited in the ability to provide the necessary uniformity required for applying a satisfactory electroplated thin film to a substrate for magnetic recording head production.
Even the continuous flow or flushing of electroplating composition forced across a stationary substrate, in lieu of mechanical agitation, causes uneven boundary layer flow patterns to form thus causing non-uniform films.
The foregoing illustrates limitations of the known prior art. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations as set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.